docs: def reprioritize(self, priority, element):
          """Updates the priority of an element.
  
          :raises: ValueError -- No such element in the priority queue.
  
          """
          if element not in self.element_finder:
              raise ValueError("No such element in the priority queue.")
          entry = self.element_finder[element]
          self.add_element(priority, element, entry[1])
          entry[1] = self.INVALID